Back-to-Back Belts Drive Filament In This Unique Extruder Design

Belt-drive 3D-printer extruder

It’s hard to say when inspiration will strike, or what form it’ll take. But we do know that when you get that itch, it’s a good idea to scratch it, because you might just end up with something like this cool new design for a 3D printer extruder as a result.

Clearly, the world is not screaming out for new extruder designs. In fact, the traditional spring-loaded, toothed drive wheel on a stepper really does the job of feeding filament into a printer’s hot end just fine, all things considered. But [Jón Schone], aka Proper Printing on YouTube, got the idea for his belt-drive extruder from seeing how filament manufacturers handle their products. His design is a scaled-down version of that, and uses a pair of very small timing belts that run on closely spaced gears. The gears synchronize the movement of the two belts, with the filament riding in the very narrow space between the belts. It’s a simple design, with the elasticity of the belt material eliminating the need for spring pre-loading of the drive gears.

Simple in design, but not the easiest execution. The video below tells [Jón]’s tale of printing woe, from using a viscous specialty SLA resin that was really intended for a temperature-controlled printer, to build tank damage. The completed extruder was also a bit too big to mount directly on the test printer, so that took some finagling too. But at the end of the day, the idea works, and it looks pretty cool doing it.

As for potential advantages of the new design, we suppose that remains to be seen. It does seem like it would eliminate drive gear eccentricity, which we’ve seen cause print quality issues before.

[BaldPower] tipped us off to this one. Thanks!

18 thoughts on “Back-to-Back Belts Drive Filament In This Unique Extruder Design

  1. Well that’s a new kind of printable extruder, a resin-printed extruder for an FFF printer. To be honest it seems much better suited to the job (and I say this as someone running a printed extruder on my ancient printer). Now I need a resin printer for my filament printer 😁

  2. I doubt that the belt that is between the pulleys on each side is contributing much at all to the push on the filament. I think that simply using a couple rubber pulleys would push just as hard.

  3. I tried almost the same thing three years ago, and found that the filament would slip, except when the drive pulleys are so tight that the belt no longer contributes to the drive. Then I might as well stick with two opposing wheels.
    For the belt to contribute significantly along its length, it would have to be supported by a series of small bearings, and that becomes too complicated.

    1. It would be interesting to cross this with the spiral roller extruder featured on here not that long ago.
      Perhaps having one long belt looped around in a toroid shape around the filament, the contact area being slanted with respect to the filament.

      Or perhaps the filament could be inside a thin tube and air could be sprayed down between the filament and the tube wall, so it was pushed along a bit like a Tesla turbine.

      There are still plenty of options for different means of extrusion. Some better suited than others.

  4. I’m definitely a 3D printing noob, but . . . I don’t see what’s wrong with the typical toothed wheel filament drive, or what makes this enough better to be worth the effort.

    On the other hand, this is HackADay, not PracticalApplicationADay, so “because I can” is a valid reason to tackle any challenge.

  5. This could potentially be super useful for flexibles. Geared extruders can sometimes chew up flexibles, but I feel like flexibles would move through a belt extruder much nicer. Kind of like how vehicles with belts instead of wheels drive smoothly on soft snow rather than sinking into the snow and getting stuck.

  6. “…the traditional spring-loaded, toothed drive wheel on a stepper…”
    Am I the only person who doesn’t use springs anymore? Just curious. I stopped using them in 2013 or so when filament started getting higher quality and we didn’t need to worry about diameter inconsistency.

    IMHO…springs give inconsistent “bite” into the filament which varies by filament type. Really what you are looking for is a consistent depth of bite which does not vary. Not tight enough to crush, not loose enough to chew.

    Depth is more important than spring pressure.

  7. While i see why people have said why do I need this, hobbed gears work well enough. And yes they do but proper printing made this for flexible filament. And seeing that video makes me want it. Its sooo much better at flex that if it can just match that good enough everywhere else id use it on alll my machines

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